Welcome to the forums.
As you know, you do not need a degree for the regional airlines.
For the legacy major airlines, United, American, Delta, Hawaiian, FedEx and UPS you will absolutely need a college degree. I am aware that United’s application page says “preferred” and that means exactly that. United has literally thousands of applications on file, they prefer ones from pilots with college degrees, so that is what they hire. I am good friends with a gentleman that is involved in hiring for United, he had informed me that he is not aware of any pilots that have been hired in the last several years without college degrees.
A job at one of the legacy majors is a highly sought after position with excellent pay and benefits. The airlines have their choice of applicants and the reality is that they only hire applicants with degrees. I highly doubt that this changes anytime soon.
As for Spirit, Virgin, etc. While some pilots do consider these to be “major” airlines, they are certainly on a lower tier than the legacy majors. By this I mean that they are mostly domestic airlines that have lower compensation and less impressive benefits. It is not at all uncommon for pilots to leave airlines like this for the legacy carriers as the legacies are far more desirable places to work.
I would point out that while your friends without degrees have made it to the lesser majors, they have not yet made it to the legacy carriers and my money says they won’t anytime soon. If I were you, I would put a lot more confidence in what Adam and I, two pilots that have made it to the legacies, say than two pilots who have not made it, but think that they will.
Bottom line, if you would like to someday work for a legacy major airline, making $300k+ as a Captain, you will need to obtain an undergraduate degree.